Kidney Week

Abstract: SA-PO200

The Role of DDR1 in Podocyte Lipotoxicity and Progression of Alport Syndrome

Session Information

• Glomerular: Cell Biology
  November 04, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Glomerular

• 1003 Glomerular: Cell Biology

Authors

• Kim, Jin Ju, Katz Family Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida, United States

Jin Ju Kim,

• Molina David, Judith T., Katz Family Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida, United States

Judith T. Molina David,

• Varona Santos, Javier T., Katz Family Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida, United States

Javier T. Varona Santos,

• Prunotto, Marco, F. Hoffmann-La Roche Ltd., Basel, Switzerland

Marco Prunotto,

• Merscher, Sandra M., Katz Family Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida, United States

Sandra M. Merscher,

• Miner, Jeffrey H., Washington University School of Medicine, St. Louis, Missouri, United States

Jeffrey H. Miner,

• Fornoni, Alessia, Katz Family Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida, United States

Alessia Fornoni,

Background

The GBM is primarily composed by laminin and Collagen type IV. De novo production of collagen type I (Col I) has been observed in a mouse models of Alport Syndrome (AS-Col4a3KO). Discoidin-domain-receptor1 (DDR1) is a unique receptor tyrosine kinase that is activated by collagens. Deletion of the DDR1 in Col4a3KO mice improves survival and renal function. However, how DDR1 activation by aberrant collagen production contributes to podocyte injury and proteinuria is poorly understood.

Methods

Differentiated human podocytes were serum starved, followed by 18hrs treatment with 50ug/mL Col I (Corning). Podocyte lipid content was determined by BODIPY 493/503 and Cell Mask Blue staining. Free Fatty acid (FFA) uptake assessed using the fluorometric free fatty acid uptake kit (abcam). Col4a3KO mice (Jackson Laboratory) were utilized for the determination of kidney cortex DDR1 phosphorylation. HEK293 transfected with Dominant active (DA) and dominant negative (DN) constructs were utilized in selected experiments.

Results

DDR1 phosphorylation was increased in kidney cortex from Col4a3KO mice (p<0.05), whereas the expression of podocin and synaptopodin was decreased. pDDR1 correlated with blood urine nitrogen (BUN, R² =0.7, p<0.01). In vitro, podocyte DDR1 was phosphorylated by Col I at 18 hours. Increased intracellular lipid accumulation (p<0.05) and FFA uptake (p<0.001) were also observed in Col I treated podocytes. DDR1 DA transfected HEK293 cells showed increased expression of CD36, a protein involved in FA uptake, and FFA uptake compared to cells transfected with DDR1 WT and DN (p<0.05). Glomeruli isolated from Col4a3KO mice showed increased lipid deposition and expression of CD36.

Conclusion

Our data suggest that col I-induced/DDR1-mediated lipotoxicity may represent a novel mechanism leading to podocyte injury in AS.

Funding

• Commercial Support –